Is starvation mode real?

What is “starvation mode”?

When people say "starvation mode", they typically mean that if your calories are too low, your body starts storing food instead of losing more because it is "hanging on to calories". The theory is, because you are in fight or flight mode, your body has decided it will not lose weight and will instead GAIN weight because you aren't giving it enough food.

This doesn't happen. Your body can't just produce more energy out of nowhere. You're not going to gain weight from not eating enough. That's like an empty bank account suddenly making lots of money just because it is empty (as much as that would be freaking awesome). YOU have to be the one to put money in there. If more money is going in than going out, you will have a net increase. Your bank account isn't going to say "hey, I'm getting really low, I better start gaining money". If you aren’t putting any in, it’s not going to get any bigger.

So starvation mode—not happening. Doesn’t exist. There is something else that happens as you diet though.

adaptive thermo-whatnow?

Now here's what DOES happen when you diet...it's called "adaptive thermogenesis" or "metabolic adaptation". It just means that whatever calorie level you give your body, it will respond to that calorie level. Low or high.

If you start overeating, your body will respond by increasing calorie expenditure through a couple different mechanisms: increase heat release (do you notice you get really hot when you overeat?), you’ll start fidgeting more, moving around more, body processes start moving faster, you’ll likely burn more in you workouts. The result is sometimes that you put yourself back in a calorie deficit because your body has started to burn so many more calories and you aren’t able to keep up with your food intake. Now keep in mind, this only happens to a point. If you chronically overeat and your body can’t keep up, this is where we get fat storage.

On the flip side, if your start undereating (like when you're dieting), your metabolism starts to adapt to this level as well. You start moving less, producing less heat (notice how you’re cold when you diet), workouts start getting less effective, you can even start to blink more slowly! As a result, a calorie level that was once working for you to lose weight will start to become less and less effective as your body works to preserve energy. Your maintenance calories (how many calories you maintain your weight on) will start to drop to the calorie level you’re currently eating. When you plateau in a diet, this is typically what is happening. It is normal and expected, but is also the reason you want to be careful not to drop your calories too much too fast at the beginning of a diet. If you are already eating a super low amount of calories, plateau, and then need to drop calories again, you might be dangerously under-consuming nutrients.

Adaptive thermogenesis is like when your pay scale changes. Say you get a pay raise. Yay! Now you can pay off your debts, go on vacation, and buy that TV you were looking at (calorie expenditure). But wait...now you have a pay cut. Dang. Now you have to cut back on extra spending. Your body does the same thing in response to how many calories you are giving it.

a diet after the diet

As you get further in a diet, your body starts burning less and less calories. If you go for too long, that will become your new maintenance. That's why it is so important to have a plan for AFTER the diet. For example, if you ended your diet at 1500 calories and your body had adapted to that, and you suddenly start eating 2500 calories again, you will be in a 1000 calorie surplus!! That's a ton!! This is when reverse dieting becomes important. Depending on how long you’ve been dieting and how adaptive your metabolism is (how much and how fast it adapts to your calorie level), you may need to start incrementally building calories back up to maintenance so you don’t gain weight.

Sometimes, when you start to build calories back up, your body will start to lose weight again. Remember when we talked about adaptive thermogenesis happening in both directions? Your body starts to burn more calories because it is getting more calories. Calorie balance still applies here. Yes you are eating more, but you are also burning more. You didn’t suddenly start losing weight in a calorie surplus. That doesn’t happen.

So always remember…anything that sounds magical or unexplainable in nutritional science usually comes down to a simple answer when we dissect the problem.